diff --git a/MagickCore/cache.c b/MagickCore/cache.c
index 4cc6537..de85fc3 100644
--- a/MagickCore/cache.c
+++ b/MagickCore/cache.c
@@ -4885,6 +4885,62 @@
% o exception: return any errors or warnings in this structure.
%
*/
+
+static MagickBooleanType SetCacheAlphaChannel(Image *image,const Quantum alpha,
+ ExceptionInfo *exception)
+{
+ CacheInfo
+ *cache_info;
+
+ MagickBooleanType
+ status;
+
+ ssize_t
+ y;
+
+ assert(image != (Image *) NULL);
+ assert(image->signature == MagickSignature);
+ if (image->debug != MagickFalse)
+ (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
+ assert(image->cache != (Cache) NULL);
+ cache_info=(CacheInfo *) image->cache;
+ assert(cache_info->signature == MagickSignature);
+ image->matte=MagickTrue;
+ status=MagickTrue;
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+ #pragma omp parallel for schedule(static,4) shared(status)
+#endif
+ for (y=0; y < (ssize_t) image->rows; y++)
+ {
+ const int
+ id = GetOpenMPThreadId();
+
+ register Quantum
+ *restrict q;
+
+ register ssize_t
+ x;
+
+ if (status == MagickFalse)
+ continue;
+ q=GetAuthenticPixelCacheNexus(image,0,y,image->columns,1,
+ cache_info->nexus_info[id],exception);
+ if (q == (Quantum *) NULL)
+ {
+ status=MagickFalse;
+ continue;
+ }
+ for (x=0; x < (ssize_t) image->columns; x++)
+ {
+ SetPixelAlpha(image,alpha,q);
+ q+=GetPixelChannels(image);
+ }
+ status=SyncAuthenticPixelCacheNexus(image,cache_info->nexus_info[id],
+ exception);
+ }
+ return(status);
+}
+
MagickPrivate VirtualPixelMethod SetPixelCacheVirtualMethod(Image *image,
const VirtualPixelMethod virtual_pixel_method,ExceptionInfo *exception)
{
@@ -4909,13 +4965,13 @@
{
if ((image->background_color.matte != MagickFalse) &&
(image->matte == MagickFalse))
- (void) SetImageAlpha(image,OpaqueAlpha,exception);
+ (void) SetCacheAlphaChannel(image,OpaqueAlpha,exception);
break;
}
case TransparentVirtualPixelMethod:
{
if (image->matte == MagickFalse)
- (void) SetImageAlpha(image,OpaqueAlpha,exception);
+ (void) SetCacheAlphaChannel(image,OpaqueAlpha,exception);
break;
}
default: